Impacto da implantação do sistema integração lavoura–pecuária–floresta em latossolo de Cerrado
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2016-03-15
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Universidade Federal de Goiás
Resumo
The current situation requires actions to promote development with minimal
negative impact on the environment. Agriculture is a sector of the economy that directly
interacts with and depends on the natural ecosystem, requiring energy and natural resources.
In this respect there is a negative balance for the environment: the intense emission GHG,
the soil resource is grately degraded and natural forests are diminished. Investment has to be
made in technologies that contribute to stop this process. The recently promoted integrated
Crop-Livestock-Forest production systems (iCLFs), in addition to their other desirable
socio-economic impacts, are expected to favor the accumulation of soil organic matter and
the recovery of degraded areas, a contributing factor to avoid deforestation for opening new
areas for agriculture. We present two studies investigating the effect of an iCLF three years
after its implementation upon degraded pasture (DP), in southern Goiás State of Brazil, in
the savannah ecosystem (Cerrado) that was carried out in colaboration with the Boa Vereda
Farm near the city of Cachoeira Dourada, where the iCLF and the reference management
systems, conventional pasture (CP) and an recovered pasture (RP) were implemented. In the
first study the effect of the implementation of the iCLF, upon DP was investigated on the
total organic carbon (TOC) and total nitrogen (TN) accumulation in the soil. For that, besides
TOC and N concentrations, soil texture, bulk density (Ds) and δ¹³C were evaluated to
validate the comparability of the investigated areas under the different management systems
on the stock of TOC and N. The soil samples were collected to 1.0 m depth in eight layers
following a transect of five sampling points (repetitions). In the iCLF each sampling point
had six soil profiles placed in different positions to represent situations according to the
presence or not of trees and transition zones between trees and pasture. In the second study
the samples were collected in the previous sampling scheme. The samples were collected
down to 0.4m in 5 layers to evaluate the physical quality of the soil: bulk density (Ds),
microporosity (Mi), macroporosity (Ma), total porosity (Pt), resistance to penetration (RP).
The results of the first study showed that the management used during the implementation
of iLPF, which included soil tillage with disc plowing, influenced negatively the stock of C
and N in the 0-0.3m layer. Another factor that likely influenced the input of C and N in the
soil was the low productivityof the pasture, result of the shading by the eucalyptus trees
(Eucalyptus urograndis) on the brachiária grass (Urochloa brizantha). Considering the layer
of 0.0 - 1.0 m, the management did not influence the stock of TOC and N in the soil. In the
second study the results showed the formation of four groups on the basis of soil physical
quality, and within the iLPF there was the formation of two groups that were distinguished
by the presence or absence of trees. The presence of the trees in the iCLF created variation
of the RP and Pt in relation to the pasture of the iCLF. This may be related to the increase in
the volume of roots and more frequent trampling by the animals under the trees causing a
reduction in the pore space and consequently greater RP. A complete cycle of the iCLF
system usually ends with the cutting and replanting of trees after 5-7 years, depending on
the purpose of the production. Therefore, further studies are necessary to evaluate the
potential of the iCLF to accumulate TOC and N in the soil and their impact on its physical
quality at the end of its cycle and eventually, after several cycles of the system.
Descrição
Palavras-chave
Sistema , Pastagem , Carbono , Nitrogênio , Qualidade física do solo , System , Pasture , Carbon , Nitrogen , Soil physical quality
Citação
SILVEIRA, A. L. R. Impacto da implantação do sistema integração lavoura–pecuária–floresta em latossolo de Cerrado. 2016. 86 f. Tese (Doutorado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2016.